Known in the art is an apparatus for the electrochemical cutting of narrow grooves (DE, C, 3419503), comprising a wire or rod electrode having an auxiliary member provided on the side of the working end thereof to extend along the entire working length of the electrode. Both the electrode and the auxiliary member are moved deep into a work being machined. A power supply is connected to the electrode, an electrolyte is supplied into a gap defined between the electrode and the work so that a groove is cut in this gap. The electrolyte flows through the gap, and the dissolved material of the work is removed from the groove together with the electrolyte. Therefore, the gap is always filled with the electrolyte during the groove cutting period, and the dissolved material is removed with the electrolyte from the gap. This apparatus cannot ensure groove cutting with a uniform size lengthwise of the groove which results in a low productivity of the apparats. This apparatus cannot be used for producing triangular section specimens from fashioned surfaces with a large radius of curvature.
Known in the art is an electrical discharge cutting apparatus (FR, B, 2371997), comprising an electrode in the form of a thin disc of a copper/tungsten alloy without insulation, a drive for rotating the electrode, and a system for feeding the electrode to a surface being machine, a means for supplying electric current to the electrode. Electrolyte supplied to the working end face of the electrode also functions as cutting fluid. The electrolyte in the form of concentrated sodium nitrate is supplied in a large quantity and under a low pressure to the rotating electrode moving in the cutting plane. This apparatus makes it possible to cut grooves of rectangular section with surfaces changes in the metal structure and does not allow a confident sample of triangular section for tests to be produced, i.e. a sample of a sufficient mass to carry out measurements of metal density and of a desired cross-sectional area for counting micropores, and the like.
Known in the art is an apparatus for the electrochemical machining of fashioned surfaces (SU, A, 260786), comprising a bed, a working unit coupled thereto and comprising a pair of electrodes mounted on a drive for their rotation on the side of a fashioned surface, each of the electrodes comprising a disc, the axes of the discs extending at an angle with respect to each other, a system for feeding the working unit to the fashioned surface having a drive for vertically feeding the working unit. The electrodes are rotated by means of a single electric motor. A workpiece is held fast to the bed, and the depth of a groove being cut is set up by the drive for vertically feeding the working unit. When an electrolyte supply system is turned on for electrolyte supply to the rotating electrodes and current is supplied to the electrodes from a power supply, the electrodes are caused to move along the workpiece thereby cutting the groove.
This apparatus does not allow a sample of triangular section to be obtained during operation of the two electrodes as their profiled portions intersect each other when penetrating at full depth of the workpiece so that they can only cut a groove and cannot cut out a triangular specimen. This apparatus has a low productivity since oscillations of the electrodes are not provided in machining a fashioned surface so that much time is spent for the electrodes to move deep into a preset depth in the surface of the workpiece.